SDL_test_random.c File Reference

#include "SDL_config.h"
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "SDL_test.h"

Include dependency graph for SDL_test_random.c:

Go to the source code of this file.

Functions
void	SDLTest_RandomInit (SDLTest_RandomContext *rndContext, unsigned int xi, unsigned int ci)
	Initialize random number generator with two integers.
void	SDLTest_RandomInitTime (SDLTest_RandomContext *rndContext)
	Initialize random number generator based on current system time.
unsigned int	SDLTest_Random (SDLTest_RandomContext *rndContext)
	Initialize random number generator based on current system time.

Function Documentation

unsigned int SDLTest_Random

(

SDLTest_RandomContext *

rndContext

)

Initialize random number generator based on current system time.

Note: ...RandomInit() or ...RandomInitTime() must have been called before using this function.

Parameters

rndContext

pointer to context structure

Returns

A random number (32bit unsigned integer)

Definition at line 80 of file SDL_test_random.c.

References SDLTest_RandomContext::a, SDLTest_RandomContext::ah, SDLTest_RandomContext::al, SDLTest_RandomContext::c, NULL, and SDLTest_RandomContext::x.

Referenced by SDLTest_GenerateRunSeed().

{
  unsigned int xh, xl;

  if (rndContext==NULL) return -1;

  xh = rndContext->x >> 16, xl = rndContext->x & 65535;
  rndContext->x = rndContext->x * rndContext->a + rndContext->c;
  rndContext->c =
    xh * rndContext->ah + ((xh * rndContext->al) >> 16) +
    ((xl * rndContext->ah) >> 16);
  if (xl * rndContext->al >= (~rndContext->c + 1))
    rndContext->c++;
  return (rndContext->x);
}

void SDLTest_RandomInit	(	SDLTest_RandomContext *	rndContext,
		unsigned int	xi,
		unsigned int	ci
	)

Initialize random number generator with two integers.

Note: The random sequence of numbers returned by ...Random() is the same for the same two integers and has a period of 2^31.

Parameters

rndContext	pointer to context structure
xi	integer that defines the random sequence
ci	integer that defines the random sequence

Definition at line 41 of file SDL_test_random.c.

References SDLTest_RandomContext::a, SDLTest_RandomContext::ah, SDLTest_RandomContext::al, SDLTest_RandomContext::c, NULL, and SDLTest_RandomContext::x.

Referenced by main(), SDLTest_FuzzerInit(), and SDLTest_RandomInitTime().

{
  if (rndContext==NULL) return;

  /*
   * Choose a value for 'a' from this list
   * 1791398085 1929682203 1683268614 1965537969 1675393560
   * 1967773755 1517746329 1447497129 1655692410 1606218150
   * 2051013963 1075433238 1557985959 1781943330 1893513180
   * 1631296680 2131995753 2083801278 1873196400 1554115554
   */
  rndContext->a = 1655692410;
  rndContext->x = 30903;
  rndContext->c = 0;
  if (xi != 0) {
      rndContext->x = xi;
  }
  rndContext->c = ci;
  rndContext->ah = rndContext->a >> 16;
  rndContext->al = rndContext->a & 65535;
}

void SDLTest_RandomInitTime

(

SDLTest_RandomContext *

rndContext

)

Initialize random number generator based on current system time.

Parameters

rndContext

pointer to context structure

Definition at line 65 of file SDL_test_random.c.

References NULL, and SDLTest_RandomInit().

Referenced by main(), and SDLTest_GenerateRunSeed().

{
  int a, b;

  if (rndContext==NULL) return;

  srand((unsigned int)time(NULL));
  a=rand();
  srand((unsigned int)clock());
  b=rand();
  SDLTest_RandomInit(rndContext, a, b);
}